Techniques for compensating for high initial unloading force requirement in tape cartridge-loading mechanism

ABSTRACT

In an automatic tape cartridge loader, separating the tape from the drive motor during unloading often imposes a high torque requirement on the loader motor, for example to overcome magnetic forces strengthening engagement of the cartridge to the motor. The inventive loader utilizes one or more techniques to assist in separation of the cartridge from the motor gear. One technique involves two compression springs on the base, which apply a force opposing movement of the cartridge shuttle to its cartridge-loaded position and assist in movement of the shuttle from that position during unloading. Another technique utilizes a special cam and follower arrangement to apply different lifting forces on opposite sides of the shuttle, at least during initial movement to unload the cartridge.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/116,014, entitled “COUNTER BALANCING SPRINGS TO COPE WITH A HIGHINITIAL FORCE REQUIREMENT IN ‘VORTEX’ CARTRIDGE-LOADING MECHANISM” filedon Jan. 15, 1999, by William B. Kim, the disclosure of which is entirelyincorporated herein by reference.

This application also claims the benefit of U.S. Provisional ApplicationNo. 60/115,958, entitled “EMPLOYING TWO DIFFERENT SIZES OF CAM FOLLOWERSIN THE ‘VORTEX’ CARTRIDGE LOADER” filed on Jan. 15, 1999 by William B.Kim, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to tape cartridge loader mechanisms,for example, for loading of single-reel magnetic tape cartridges intoappropriate tape drives. One specific aspect of the invention relates toload balancing to offset magnetic clutch action so as to separate a tapecartridge from a tape drive. Another specific aspect of the inventionrelates to cam and cam follower designs for such loaders, to efficientlylift the cartridge from engagement with the tape drive motor gear.

BACKGROUND

Computers utilize a variety of magnetic media devices for the storage ofsoftware programs and data. Information recorded on the magnetic mediumtakes the form of flux transitions that represent the binary “1's” and“0's” that form the digital information. Tape cartridges, such assingle-reel tape cartridges, are commonly used in library or otherarchival data storage applications. In such applications, a user or arobotic mechanism selects a tape cartridge for processing and insertsthe cartridge into a tape drive coupled to a computer. In a fullyautomated system, a mechanism within the tape drive loads the tape fromits entry point to a position in which the tape becomes accessible forread-from and write-to operations.

A variety of different size data tape cartridges are available. Thedrives for the different size cartridges, however, must be substantiallythe same size, so as to fit within a standard size slot or spaceavailable within the framework of a personal computer or the like.Larger cartridges enable storage of more data on the tape within,however, the larger the cartridge the more difficult it is to design adrive mechanism to fit within the design envelope.

For example, some single reel cartridges are 105.4 mm wide, by 102 mmlong by 21.5 mm high. Such a cartridge, by itself fills a substantialportion of the design envelope for the tape drive. As a result, tapedrives for this type of cartridge have utilized manual loadingmechanisms. All movement and operations to load the tape cartridge intothe drive, open the tape door for access to the tape leader and engagethe tape drive gear to the drive motor gear have been manual in nature.A portion of the cartridge remains outside the drive, even in the fullyloaded position.

Data cartridge tape drives have been developed with automatic or “soft”loading and unloading of the cartridge. However, because of the size andcomplexity of the loading mechanism, these automatic loaders have beenused only in drives for smaller tape cartridges.

Also, automatic cartridge tape drives must be able to load and unloadcartridges many times without jamming or other failures. A failure of anautomatic loader mechanism may damage a tape cartridge and makes thedrive unusable until repaired or replaced. Typical design parameters fordrives available today call for the loader mechanism to continue tooperate successfully for at least 300,000 loading/unloading cycles. Forapplications with frequent cartridge replacement, such as tape librarysystems providing access to volumes of data to many users via networks,to have a truly useful life each tape loader mechanism must operatesuccessfully with little or no wear for many more cycles than even thisdesign parameter.

Automatic loader mechanisms have been developed in the past that includesome form of conveyor and/or shuttle mechanism to retract the cartridgeentirely within the drive and lower the cartridge for engagement withthe tape drive motor gear. These mechanisms are motor driven. Manycartridge tape drives use a magnet and a metal plate to form a magneticclutch, to engage the cartridge gear to the drive gear associated withthe motor. The loader motor must supply sufficient torque duringunloading to overcome the magnetic clutch forces, in order to separatethe cartridge from the cartridge drive motor. This imposes a high powerrequirement on the loader motor. To produce adequate torque typicallyrequires a larger motor and more electrical power. The high torque alsotends to wear out drive linkages quickly.

It should, therefore, be appreciated that a need exists for an automaticloading mechanism for data tape cartridges that takes up the minimumamount of space within the design envelope of the tape drive, to allowthe mechanism and the drive to handle as large a cartridge as possible.Also, a need exists for a loader mechanism of this type that isparticularly durable and can operate successfully for a large number ofloading/unloading cycles without any jams or other failures. To meetthese general needs there is a specific need for a technique to reducethe torque requirement on the loader motor needed to separate themagnetic clutch elements, to allow use of a smaller motor and reducestress and wear on loader components.

SUMMARY OF THE INVENTION

The present invention meets the above-stated needs and overcomes theproblems with prior cartridge loader systems.

The present invention relates to a loader, for automatically loading atape cartridge into a tape drive, preferably for reading and writingdata on a tape within the cartridge. The loader includes a cartridgeshuttle. The shuttle receives the tape cartridge and moves to and from aposition within the tape drive in which the cartridge is operativelyloaded into the tape drive. The loader also includes means for producinga force to assist in separating the gear within the tape cartridge fromthe gear coupled to the drive motor.

The assist force may be provided by one or more load balancing springs.In addition or alternatively, the assist force may be generated by aunique cam and follower arrangement, which applies different forces onopposing sides of the shuttle at least during initial unloading motionof the cartridge.

Thus, one aspect of the present invention relates to an automatic tapecartridge loader. The inventive loader includes a shuttle for receivingthe tape cartridge and means for moving the shuttle. The movement meansautomatically moves the shuttle to and from a position within theloader, in which a gear within the tape cartridge engages a gear coupledto a drive motor of the tape drive. In the preferred embodiments,magnetic attraction between the gears draws the two gears into secureengagement. In this aspect of the invention, the loader also includes atleast one spring. The spring produces a force opposing movement of theshuttle to the cartridge-loaded position. The spring assists in movementof the shuttle from that position, during unloading, in such manner asto assist in separating the gear within the tape cartridge from the gearcoupled to the drive motor. For example, when there is magneticattraction between the gears, the spring force helps to overcome themagnetic clutch engagement between the two gears.

In the preferred embodiment, the spring actually comprises two moresprings. Although a variety of arrangements are possible, the springstypically are compression springs attached to a base, for compression bythe cartridge or shuttle as the shuttle moves to the cartridge-loadedposition within the loader and tape drive.

The load balancing spring forces on the cartridge shuttle help toovercome the magnetic attraction and separate the gears. This reducesthe torque and/or power requirement on the loader motor during theunloading operation. The loader may use a smaller motor, and the reducedtorque tends to extend the useful life of the loader and motor.

The preferred embodiment of the shuttle includes cantilevered springsfor applying spring force toward the tape drive motor to the cartridgewithin the shuttle and for buffering the cartridge within the shuttle.The cam profiles induce motion of the shuttle slightly past thecartridge-loaded position, to produce a gap between a surface of thecartridge and an adjacent surface of the shuttle. The cantileveredsprings buffer the cartridge within the shuttle, when the shuttle movespast the cartridge-loaded position. Another aspect of the inventionrelates to a tape cartridge loader. The loader includes a conveyor and ashuttle for receiving the tape cartridge. The conveyor is mounted forlinear motion. The conveyor has two sidewalls and at least one camprofile in each sidewall. The loader includes a first cam followerbearing attached to a side of the shuttle for engagement with the firstcam profile and a second cam follower bearing attached to the oppositeside of the shuttle for engagement with the second cam profile. Thesecond cam follower bearing is larger than the first cam followerbearing. The first and second cam profiles are contoured so thatinteraction of the bearings with the first and second cam profilesduring unloading of the tape cartridge from the loader providesdifferent forces on opposing sides of the tape cartridge.

The differing forces on opposite sides of the shuttle preferably cause alift of the cartridge that is uneven. The forces may initiate lift ofeach side of the shuttle and thus the cartridge at different timesduring the unloading operation and may result in a slight skew of thecartridge with respect the plane of the motor drive gear. For example,in a preferred embodiment, the first and second cam profiles arecontoured such that motion of the conveyor during unloading causes thefirst cam profile to apply force through the first cam follower bearingprior to the second cam profile applying force through the second camfollower bearing. The plane of the gear in the tape cartridge rises atan angle with respect to the plane of the drive motor gear, instead ofparallel. In a tape drive having a magnetic attraction between the tapemotor drive gear and the gear within the tape cartridge, thesedifferences in the application of force on the sides of the cartridgehelp to overcome the magnetic attraction and separate the gears. Thisreduces the torque and/or power requirement on the loader motor duringthe unloading operation. The loader may use a smaller motor, and thereduced torque tends to extend the useful life of the loader and motor.

In the preferred embodiment, the loader also includes a frame housing.The conveyor is mounted for linear motion within the frame housing, forexample by means of follower bearings attached to the conveyor that ridein one or more linear grooves in the walls of the frame housing. Theframe housing may have a path constraint groove, with a first sectionparallel to the linear motion of the conveyor and a second sectionperpendicular to the first section. One of the cam follower bearingsattached to the shuttle also interacts with the path constraint groove,to limit motion of the shuttle to a path defined by the path constraintgroove formed in the frame housing.

In a fully automated implementation, the tape cartridge loader wouldalso include an actuator system. This system preferably includes arotatable actuator arm coupled to the frame housing, for inducing thelinear motion of the conveyor. A motor is coupled to the actuator, forexample through worm and sector gears, to drive the rotation of theactuator arm in response to a drive signal.

Another aspect of the invention relates to a tape drive incorporatingthe inventive cartridge loader. The tape drive includes a tape drivemotor and a tape drive gear coupled for rotation by the tape drivemotor. A magnet is secured to the tape drive gear for magneticallyattracting a gear within the tape cartridge. The drive also includes anautomatic loader, for loading the tape cartridge such that the tapedrive gear engages the gear within the tape cartridge and for unloadingthe tape cartridge from engagement and from the tape drive.

In this aspect of the invention, the automatic loader includes a framehousing, a conveyor and a shuttle. The conveyor is mounted in the framehousing for linear motion back and forth during loading and unloading ofthe tape cartridge. The conveyor has sidewalls, with at least one grooveformed in each sidewall. Each of these grooves has a cam profile for usein a cartridge loading operation and a cam profile for use in acartridge loading operation. An actuator, preferably in the form of aflat rotatable arm, is coupled to the conveyor. The actuator isautomatically driven so as to induce the various linear motions of theconveyor.

A first cam follower bearing, attached to a first side of the shuttle,engages the cam profiles of the first groove, and a second cam followerbearing, attached to the opposite side of the shuttle, engages the camprofiles of the second groove. The loading cam profiles of the twogrooves are contoured so that interaction with the follower bearings,during tape loading, induces a motion of the shuttle for retracting thetape cartridge into the frame housing and into engagement.

The second cam follower bearing is larger than the first cam followerbearing. Also, the unloading cam profiles of the grooves are speciallycontoured. As a result, the interaction of the followers with theunloading profiles during unloading provides different forces onopposing sides of the tape cartridge. The differing forces on oppositesides of the shuttle assist in separation of the gear within the tapecartridge from engagement with the tape drive gear.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict the present invention by way of example, notby way of limitations. In the figures, like reference numerals refer tothe same or similar elements.

FIG. 1-A is an isometric view of the loader assembly frame housing.

FIG. 1-B is an exploded isometric view of the loader assembly housingand the conveyor showing the interconnection thereof.

FIG. 2-A is an isometric view of the assembly formed by the cartridgeshuttle and the flat spring assembly, from the back side.

FIG. 2-B is an exploded isometric view of the assembly formed by thecartridge shuttle and the flat spring assembly from the front (cartridgeloading) side.

FIG. 3-A is a side isometric view, illustrating the interacting elementsof the cartridge and the cartridge shuttle, with the shuttle andcartridge inverted to show the lower-side thereof.

FIG. 3-B is a back side isometric view showing the cartridge and thecartridge shuttle in the loaded position on top of the reel motor.

FIG. 4-A is an isometric view of the loader assembly with the shuttleconveyor actuator, from the front (cartridge loading) side.

FIG. 4-B is an exploded isometric view of the loader assembly and theshuttle conveyor actuator from the front (cartridge loading) side.

FIG. 4-C is an isometric view of the cartridge loading motor and wormgear assembly.

FIG. 5-A is a detailed view of the cam follower, the cam profile and theimpact buffer spring of the shuttle conveyor actuator, at the start ofcartridge loading.

FIG. 5-B is a detailed view of the cam follower, the cam profile and theimpact buffer spring of the shuttle conveyor actuator, at the start ofcartridge unloading.

FIG. 6-A is a detailed view of the two cam profiles of the left sidewallof the conveyor and the cam followers of the shuttle cartridge ridingwithin those profiles.

FIG. 6-B is a detailed view of the cam profile of the right sidewall ofthe conveyor and the cam follower of the shuttle cartridge riding withinthat profile.

FIG. 7 is a partially exploded isometric view of the shuttle assembly,the cartridge loader motor and the tape drive base.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The several drawings depict a tape drive 1, including a base 9 and aloader assembly 11 (see e.g. FIGS. 1-B and 7). The loader assembly 11receives a tape cartridge, for example containing a magnetic tape orother tape media for storage of digital data. In the presently preferredembodiments, the cartridge is a single-reel tape cartridge containingmagnetic tape. The loader assembly 11 loads the cartridge intoengagement with a drive motor and opens a door on the cartridge toprovide access to a leader attached to the tape contained within thecartridge. A load arm assembly, not shown, connects to the leader andwithdraws the leader for coupling to a take up reel. While so engaged,the tape from the cartridge may be repeatedly wound and rewound betweenthe cartridge and the take up reel, while data is read from and/orwritten to the magnetic tape.

The tape drive 1 may be loaded manually, or the tape drive may receive acartridge from another mechanism, for example from a robotic tapeselector in a tape library system. For ease of description, the textbelow refers to insertion of a tape by a user. Those skilled in the artwill recognize that this “user” may be a human operator or an automateddevice or system for selecting one of many available tapes, for examplein a library of such tapes, and inserting the selected tape through abezel opening into the tape drive.

The tape drive 1 may be orientated in any convenient direction. Forpurposes of discussion, it is assumed that the opening for insertion ofthe tape cartridge corresponds to the “front” of the drive, and thewidth of the opening to receive the cartridge would be horizontal. Theuser would insert the cartridge with a front-to-back motion. In severalof the drawings, such as 1-B and 7, the base 9 and/or the loaderassembly 11 of the drive 1 are shown in a position to receive thecartridge from the front, and the loader assembly 11 retracts and lowersthe cartridge during loading, to engage the tape within the drive. Forconvenience of discussion, references to horizontal, vertical, varioussides and front and back will assume such a normal orientation of thedrive 1, and where appropriate to a corresponding orientation of thecartridge, as shown in those drawings. The orientations shown and thedescriptive references thereto, however, are for purposes ofillustration and example only.

The tape drive 1 includes a base 9 and a loader assembly 11 (FIG. 7).The loader assembly 11 comprises a frame housing 13 (FIGS. 1-A, 1-B). Ifthe base 9 is horizontal, as shown in FIG. 7, the loader assembly framehousing 13 is secured to the top side of the base 9, for example byrivets or the like. As discussed more later, the base 9 also supportsone or more springs 161 producing forces to assist in separating thecartridge from the drive motor during unloading.

With reference to FIG. 1-A, the loader assembly frame housing 13comprises a right sidewall 15, a planar top plate 17 and a left sidewall19. The sidewalls 15, 19 are substantially perpendicular to the topplate 17. The right sidewall 15 includes a horizontal shoulder at thebottom with two or more holes therethrough, to facilitate attachment ofthe sidewall to the top of the base (FIG. 7). The left sidewall includestwo or more horizontal holes therethrough, to facilitate attachment tothe side of the base.

Each sidewall 15, 19 of the loader assembly frame housing 13 includestwo linear travel grooves 21. In the illustrated embodiment, the grooves21 are adjacent to the top of the respective sidewall and extendparallel to the top plate 17. The conveyor includes a cam followerbearing for interaction with each of the linear travel grooves. In theillustrated implementation, these follower bearings comprise machinescrews or pins and bearings mounted for rotation about the pins. A pin23 passes through a bearing 25 and is attached to a hole in the matchingsidewall of the conveyor 27. The bearings 25 are slightly smaller indiameter than the vertical height of the linear travel grooves 21. Thelinear grooves 21 and the associated cam follower bearings 25 providevertical support for the conveyor 27. Each of the bearings 25 travelsalong one of the linear grooves 21, to provide a precise front-to-backlinear travel for the conveyor 27.

The top plate 17 of the loader assembly frame housing 13 includesanother linear travel groove 29. In the illustrated embodiment, thegroove 29 is substantially centered in the top plate 17 between the twosidewalls 15, 19. The groove 29 is somewhat longer than the individualgrooves 21. The conveyor 27 includes two cam follower bearings forinteraction with the top linear travel groove 29, for example formed bypins 31 and bearings 33. A pin 31 passes through a bearing 33 and isattached to a hole in the matching top plate of the conveyor 27. Thebearings 33 are slightly smaller in diameter than the width of thelinear travel groove 29. The bearings 33 travel along the linear groove29 in the top plate 17, to limit lateral movement of the conveyor duringfront-to-back linear travel of the conveyor 27.

As shown, the front pin 31′ actually is somewhat taller than the backpin 31, and the pin 31′ passes through two bearings 33, 33′. The lowerbearing 33 engages the linear travel groove 29, for control of the frontto back motion of the conveyor 27. As discussed more later, the upperbearing 33′ forms a cam follower bearing engaging a cam profile withinan actuator arm, which induces the movement of the conveyor 27. The backpin 31 and bearing 33 form a path guide bearing.

The sidewall 15 of the frame 13 includes a path constraint groove 35.The groove 35 includes a first linear section extending horizontally(parallel to the top plate 17) in the front-to-back direction along thesidewall. A second linear section, at the back of the groove, extendsvertically downward.

The conveyor 27 comprises a right sidewall 37, a top plate 39 and a leftsidewall 41. The sidewalls 37, 41 are substantially perpendicular to andextend vertically downward from the top plate 39. The sidewalls of theconveyor 27 include inclined cam profiles 43, 45. Specifically, theright sidewall 37 includes one inclined cam profile 43, approximatelymid-way from front to back along the wall, for raising and lowering thecartridge shuttle (shown in other drawings). The left sidewall 41includes two cam profiles 45, for use in raising the left side of thecartridge shuttle.

The linear grooves 21, 29 and associated cam follower bearings coupledto the conveyor 27 enable front-to-back linear motion of the conveyorwithin the loader assembly frame housing 13. In a preferred embodiment,the conveyor moves 31.4 mm horizontally. The inclined cam surfaces 43,45 in the sidewalls 37, 41 of the conveyor 27 produce a verticalmovement of the cartridge shuttle assembly. The cam follower bearingengaging the inclined cam profile 43 also engages the path constraintgroove 35 in sidewall 15. The groove 35 controls the direction andextent of travel of the cartridge shuttle during loading and unloadingoperations.

FIGS. 2-A and 2-B illustrate the structure of the cartridge shuttleassembly 47. FIG. 2-A is an isometric view from the back of theassembly, whereas FIG. 2-B is an isometric view from the front of theassembly. This assembly 47 essentially comprises two elements, thecartridge shuttle 49 and a flat spring assembly 51.

The cartridge shuttle 49 comprises a right sidewall 53, a planar bottomplate 55 and a left sidewall 57. The sidewalls 53, 57 are substantiallyperpendicular to and extend vertically upward from the bottom plate 55.As shown in FIG. 2-B, the left sidewall 57 of the cartridge shuttle 47includes two extruded features 59, which extend toward the center of theshuttle assembly 47. As the user inserts a tape cartridge into theshuttle, the extruded features 59 engage the left side of the tapecartridge and push the cartridge toward the right side of the cartridgeshuttle assembly 47. Essentially, the features 59 serve to justify thecartridge to the right, during loading of the cartridge into the drive.The features 59 maintain the cartridge in the justified positionthroughout loading, data read/write operations and unloading of the tapefrom the tape drive.

The back end of the bottom plate 55 includes two extensions near theleft and right edges of the plate. These extensions include verticalprojections 61, which serve as cartridge stops. When the user insertsthe cartridge, the user pushes the cartridge from front-to-back insidethe tape cartridge shuttle assembly 47. The projections or stops 61limit the travel of the cartridge from front-to-back into the tapecartridge shuttle assembly 47.

Each sidewall 53, 57 connects to an attachment plate 63, 65 bent back atright angles to the sidewalls toward the top-center section of theshuttle assembly 47. Each of the attachment plates includes four holesfor receiving rivets 66, to secure the flat spring assembly 51 to thecartridge shuttle 49.

The attachment plate 65 extends somewhat more to the rear of theassembly 47 (FIG. 2-B), to allow attachment of a sensor switch support67 (FIG. 2-A). The sensor switch support 67 in turn supports acartridge-in sensor switch 69 with a flexible cable guide 71 for theelectrical cable connection to the switch. When the user inserts thecartridge, the user pushes the cartridge from front-to-back inside theassembly 47 until the cartridge engages the stops 61. As the cartridgeapproaches the stops 61, it also actuates the sensor switch 69. Theswitch 69 provides a signal to the drive control circuitry (not shown)indicating insertion of a cartridge and triggering actuation of theloader motor assembly, as discussed more later.

The right sidewall 53 includes a bent feature 73 extending inwards fromthe back edge of the wall. The feature 73 is positioned along the wall53 and extends inward an appropriate distance, so as to engage a slidingtape door on the right side of the tape cartridge. As the cartridgeenters the shuttle and travels to the back thereof, the feature 73engages and pulls the tape door of the cartridge toward the rear of thecartridge. This opens the tape door of the cartridge, and enables accessto the tape leader pin by a load arm assembly (not shown).

Near the lower front corner, each sidewall 53, 57 includes a rectangularopening 74, which extends somewhat into the bottom plate 55. Theopenings 74 enable mounting of flat springs and extension of the springsinto the interior of the cartridge shuttle assembly 47. The springs (oneof which appears in a later drawing) engage notches in the tapecartridge.

Consider now the flat spring assembly 51. As noted, this assembly 51 ismounted across the top of the cartridge shuttle 49. The spring assembly51 includes a front tip 75 for vertically guiding the cartridge as theuser inserts the cartridge through a bezel opening (not shown) into thetape drive. The assembly 51 includes a plate 77 for actual attachment ofthe spring assembly 51 to the plates 63, 65 associated with thesidewalls of the cartridge shuttle 49 by the rivets 66. The plate 77 inturn supports four cantilevered flat springs 79. Two of the springs 79extend to the right of the assembly 51, along the front and the back ofthe assembly (FIG. 2-B). The other two springs 79 extend to the left ofthe assembly 51, along the front and the back of the assembly. Eachspring 79 includes a cartridge pressure button 81 extending down throughthe distal end of the spring. The buttons 81 contact the top surface ofa cartridge when contained within the cartridge shuttle assembly 47. Thebuttons 81 transfer spring pressure downwards from the cantilevered flatsprings 79 to the cartridge, to assist in engaging the tape reel of thecartridge with the tape chuck of the drive motor and to buffer thecartridge vertically within the shuttle, as discussed more below.

The cartridge shuttle assembly 47 together with the conveyor 27 receivethe cartridge, and they enable horizontal and vertical motion from theposition where the cartridge passes through the bezel opening into thetape drive to the cartridge-loaded position where the tape reel engagesthe drive motor chuck and the actual tape may be withdrawn from thecartridge for data read/write operations. To facilitate this motion, thesidewalls 53, 57 include attachment holes 83, for attachment of camfollower bearings to the assembly 47. As visible in the front isometricview of FIG. 2-B, the right sidewall 53 includes a single attachmenthole 83 approximately mid-way along the sidewall, for attachment of acam follower bearing to engage the cam profile 43 of the right sidewall37 of the conveyor 27 as well as the path constraint groove 35 in theright sidewall 15 of the frame housing 13. As visible in the rearisometric view of FIG. 2-A, the left sidewall 57 includes two attachmentholes 83. These two holes enable attachment to the cartridge shuttle 49of cam follower bearings to engage the inclined cam profiles 45 of theleft sidewall 41 of the conveyor 27.

FIG. 3A shows a tape cartridge 91 inserted in the cartridge shuttleassembly 47. In this drawing, the tape cartridge and the shuttleassembly are turned upside down, to show the underside thereof. Asshown, the bottom plate 55 of the cartridge shuttle 49 includes anopening 93. The opening 93 extends laterally across the central portionof the bottom plate and provides access to the bottom of the cartridge91, specifically to the central drive gear 95 of the tape cartridge. Thedrive gear 95 is coupled to the bottom of the tape spool within thecartridge 91. The drive gear 95 comprises a metal or magnetic plate 97around the coupling to the central shaft and downwardly extending gearteeth 99 around the periphery of the gear. The material of the plate 97is such as to enable attraction of the cartridge drive gear to a magnetwithin the motor gear.

FIG. 3A also depicts the tape drive motor 101. As shown, the motorincludes a vertical drive shaft 103, driven to rotate by theelectromagnetic components of the motor. A motor drive gear 105 issecured to the upper end of the drive shaft 103. The motor drive gear105 includes a ring-shaped magnet 107 about the end of the shaft 103 anda ring of upwardly extending gear teeth 109 around the periphery of thegear. The size of the teeth 109 and the diameter of the ring of teeth109 correspond to those of the gear teeth 99 on the cartridge drive gear95, to enable the two sets of teeth to mesh when the cartridge is in itsloaded position.

The magnet 107 on the motor drive gear 105 interacts with the plate 97of the cartridge gear 95, as the shuttle assembly 47 lowers thecartridge 91 to the position shown in FIG. 3B, to provide a magneticclutch action. The magnetic force between the magnet 107 and the plate97 pulls the cartridge gear 95 toward the motor drive gear 95 to providea positive mesh between the two sets of peripheral gear teeth 99, 109.

FIG. 3A shows two additional openings 111 near the back corners of thebottom plate 55 of the cartridge shuttle 49. When a cartridge 91 isfully inserted into the shuttle assembly 47, as shown, the openings 111provide access to small holes 113 formed in the bottom of the cartridge91. These holes are used for registration with features on the baseplate, as the loader assembly lowers the cartridge into its full,operational position, as discussed more later with regard to FIG. 7.

FIGS. 4-A to 4-C illustrate the elements of the automatic actuatorsystem, for producing the linear back and forth movements of theconveyor. FIG. 4-A depicts the loader assembly 11 with the shuttleconveyor actuator arm 121 and the actuator guide 123 mounted on the topof the frame housing 13. The actuator arm 121 includes a bearing opening125 (FIG. 4-B). The bearing opening 125 is sized slightly larger thanthe pivot pin 127, securely attached to the top of the frame housing 13(FIG. 4-B). The pivot pin 127 and opening 125 form a bearing enablingrotational motion of the arm 121 about the axis of the pin and opening.Surrounding regions of the arm include raised bosses, to insure adequatestrength and rigidity.

The actuator arm 121 is a relatively flat member extending from thepivot axis across the top of the frame housing 13. The flat constructionof this arm minimizes the vertical space occupied by the means foractuating the conveyor in response to the motive force of the loadermotor assembly.

The portion of the periphery around the end of the arm 121 centeredabout the axis of the pin and opening is semicircular. Along a portionof the semicircular end of the arm 121, the arm includes a series ofsector gear teeth 129. The sector gear teeth extend out radially, toedges that are substantially vertical.

FIG. 4-C presents an isometric view of the loader motor assembly 131.The assembly 131 includes an electromagnetic motor 133, a gear reductionbox, an encoder, a gear train and a worm gear 135. The assembly alsoincludes a bracket 137 for securely attaching the assembly 131 to thebase (see FIG. 7). The teeth of the worm gear 135 essentially form ascrew, which rotates about a horizontal axis. The motor 133, gearreduction box, and gear train drive the worm gear 135 to rotate aboutits axis. The gear 135 may rotate clockwise or counterclockwise aboutits axis, depending upon the drive signals applied to the motor 133, todrive the various operations of the loader assembly 11.

When assembled, the teeth of the worm gear 135 of the motor assembly 131engage the sector gear teeth 129 on the periphery of the end of theactuator arm 121. The motor assembly 131 rotates the worm gear 135, andthe interaction between the teeth of the gear 135 and the teeth of thegear 129 causes the actuator arm 121 to rotate about the pivot axisformed by the pin 127 and the opening 125.

Rotation of the worm gear 135 in a first direction will cause theactuator arm 121 to rotate about its axis in a clockwise direction (whenviewed from the top as in FIG. 4A). For example, during a loadingoperation, this drive operation would move the actuator arm from theposition shown in FIG. 4A to a position around to the right. Laterrotation of the worm gear 135 in a second direction will cause theactuator arm 121 to rotate about its axis in a counterclockwisedirection to drive the actuator arm back to the position shown in FIG.4A, to unload a cartridge.

The actuator guide 123 is mounted on the top plate of the frame housing13. The front and back ends of the guide 123 include bosses, to supportthe guide at a distance above the top plate 17 of the housing frame 13.A leading edge of the actuator guide 123 extends to the right, above thepath of travel of the distal or radial end of the actuator arm 121.Adjacent to the groove 141, the radial end of the arm 121 travels in thespace formed between the top of the frame housing 13 and the undersideof the guide 123. The guide 123 limits any possible upward movement ofthat end of the arm 121, to prevent twisting of the arm during itsmovement to load and unload cartridges from the tape drive 1.

The top surface of the guide 123 is the actual top of the loadermechanism. The actuator arm 121 and the guide 123 provide a particularlylow profile and make efficient use of space within the design envelopefor the drive.

As shown by the discussion above, the drive motor assembly 131 drivesthe actuator arm 121 to rotate. The conveyor 27, however, moves in alinear direction along the front-to-back axis of the loader assembly 11.To convert the rotation of the actuator arm 121 to a linear motion fordriving the conveyor 27, the arm 121 includes a curved groove 141. Thefront and back edges of the groove 141 form cam profiles for cartridgeloading and unloading. The groove is wider than the diameter of theassociated cam follower bearing so that when the bearing follows oneedge or profile of the groove there is a gap between the bearing and theopposite edge of the groove.

FIG. 4-B shows the cam follower bearing 33′ attached to the conveyor,for interaction with the edges of the groove 141. The lower bearing 33on the front pin and the back bearing 33 interact with the linear travelgroove 29, as discussed above relative to FIG. 1-B. The camming actionof the edges of the groove 141 moves the follower bearing 33′ back andforth in a linear fashion along the groove 29 in the top plate 17 of theframe housing 13. This motion of the follower 33′ in turn induces linearmovements of the conveyor 27.

The actuator arm 121 includes a pivot 145, projecting upwards from theupper surface of the arm near one end of the groove 141. The arm 121also supports a torsion spring 147, which serves as an impact buffer.The coil of the impact buffer spring 147 fits around the outside of thepivot 145. A retainer 149 attaches to the pivot 145 to hold the spring147 in place. The retainer is a flat member threaded on the bottom forattachment to matching threads of the pivot 145. The retainer has flatsides to enable a technician to turn the retainer to attach or detach itfrom the pivot. This design of the retainer minimizes the heightthereof, to keep the loader mechanism within height constraints for thedesign profile of the drive.

In the preferred embodiments, the bottom, the left and right sides, andthe back of the drive 1 are enclosed by a housing (not shown). Becauseof the small height allowed for the drive, the housing does not coverthe arm 121 and the guide 123 on the top of the loader.

FIGS. 4-A and 4-B also show the interaction of the home position sensorswitch 151 with the cam follower bearing 153 attached to the shuttle.Specifically, the frame housing 13 supports an attached micro-switch 151near the front end of the horizontal section of the path constraintgroove 35 (FIG. 4-B). The home position sensor switch 151 provides acontrol signal to stop the loader motor operation when it detects thecam follower 153 attached to the shuttle approaching the front end ofthe groove 35, at the end of an unloading operation.

In FIG. 4-B, one of the two flat springs 155 is visible through thesidewall opening 74 (FIG. 2-B). The springs 155 register with notches inthe lower side edges of the tape cartridge housing, when the tape isfully inserted into the shuttle assembly.

FIGS. 5-A and 5-B show the interaction of the groove 141, the camfollower bearing 33′ and the spring 147 in somewhat more detail. Thespring 147 comprises two arms extending outward from the coil about thespring pivot. One arm engages a boss formed on the top of the actuatorarm and remains relatively stationary with regard to the arm and thepivot. The other arm extends from the coil outward essentially along theradial dimension of the arm 121. The coil of the spring 147 isdimensioned such that the spring applies a counterclockwise force. Thisforce normally biases the follower bearing 33′, and thus the conveyor 27back toward the bezel opening. The spring 147 serves as an impactbuffer, to absorb at least some of the force if any imparted to theconveyor by insertion of a tape cartridge through the opening into thedrive.

The contour of the arm of the spring is carefully designed as shown tomaintain direct contact with the bearing 33′ as the bearing moves alongthe cam profile edges of the groove. As shown in FIG. 5-A, the spring147 normally biases the cam follower bearing 33′ forward against the camprofile formed by the front edge 141′ of the groove. This front edge141′ serves as the cam profile during clockwise rotation of the actuatorarm 121 to load a tape cartridge into the drive. The cam profile 141′pushes the follower bearing 33′. Specifically, as the arm 121 rotatesfrom the position shown in FIG. 5-A, the follower bearing 33′ engagesthe edge 141′ and moves to the right as shown by the arrow. The force onthe follower bearing during the loading operation is controlled by thecam profile of the edge 141′. As the bearing 33′ follows the profileedge 141′, the bearing 33′ also engages and moves inward along thecontour of the moveable arm of the spring 147. The serpentine contour ofthe edge 141′ is carefully designed so that as the arm 121 rotatesclockwise the edge 141′ maintains a constant 90° contact and pressurewith respect to the circumferential surface of the follower bearing 33′.The arm of the spring 147 maintains similar 90° contact with thefollower bearing 33′.

FIG. 5-B illustrates engagement of the follower bearing 143 with theback edge 141″ of the groove, during movement of the actuator arm 121 tounload the tape cartridge from the drive. Both the cam profile 141″ andthe spring 147 push the follower bearing 33′ during unloading. As thearm 121 rotates counterclockwise, to the left from the position shown inFIG. 5-B, the follower bearing 33′ engages the edge 141″ and moves backto the left as shown by the arrow. The force on the follower bearingduring the unloading operation is controlled by the cam profile of theedge 141″ and the tension of spring 147. As the bearing 33′ follows theprofile edge 141″, the bearing 33′ also engages and moves outward alongthe contour of the moveable arm of the spring 147. The profiles of theedge 141″ and of the arm of the spring 147 are designed to push thecircumference of the follower bearing 33′ with a 90° force angle,throughout the counterclockwise movement of the actuator arm. When theactuator arm 121 stops moving counterclockwise (position shown in FIG.5-A), the force of the spring 147 returns the follower bearing 33′ tothe position where it engages the front edge 141′ of the groove, for thenext subsequent cartridge loading operation.

Hence, the operation of the loading motor assembly 131 causes theactuator arm 121 to rotate, and the cam profiles of the groove 141 movethe follower 33′ and the attached conveyor 27 back and forth along alinear path during loading and unloading operations. The directperpendicular (90°) engagement of the cam profiles and the spring arm tothe cam follower bearing maximizes the force transferred from theactuator arm to the conveyor. The tape cartridge shuttle is supported byfollower bearings in cam profile grooves in the conveyor. The camprofiles together with the path constraint groove in the frame housingserve to convert the linear movement of the conveyor into a right anglemovement of the shuttle and the cartridge within the shuttle. Forexample, during the loading operation, this right angle movement movesthe shuttle and cartridge back into the drive and down into theoperational position.

FIGS. 6-A and 6-B depict the cam profile and follower arrangement,including the cam profiles 43, 45 formed within the sidewalls 37, 41 ofthe conveyor 27 and the associated follower bearings. Both drawingsdepict the cam profiles as if viewed from the right side. Each camprofile comprises an angled groove, with a short section having a lowpressure angle, a bend and a somewhat longer inclined section. In eachcase, the upper edge 43′ or 45′ of the groove serves as the cam profileengaging the corresponding cam follower bearing during loading of a tapecartridge. The lower edge 43″ or 45″ of the groove serves as the camprofile engaging the corresponding cam follower bearing during unloadingof a tape cartridge.

The two grooves 45 forming the cam profiles in the left sidewall (FIG.6-A) have the same dimensions, specifically to facilitate a cammingaction with a 4 mm diameter cam follower bearing 157. The groove 43forming the cam profile in the right sidewall (FIG. 6-B) has a similarcontour, but this groove is wider so as to interact with a 5 mm diametercam follower bearing 153.

The contour of right side conveyor wall 37 includes a notch enablingaccess through the tape door of the cartridge. Consequently, the wall 37only has room for one groove 43. To carry the requisite load, thebearing 153 is larger than the bearings 157. To accommodate the largerbearing, the groove 43 is larger than the grooves 45. As a result, theedges 43′, 43″ present somewhat different cam profiles than do the edges45′, 45″.

As the actuator arm moves the conveyor back into the frame housingduring a loading operation, the frame sidewalls 37, 41 move from left toright in the orientation shown in FIGS. 6-A, 6-B. Initially, the pathconstraint groove 35 causes the cam follower bearing 153 on the shuttleto move laterally. However, when the follower bearing 153 reaches theend of the horizontal section of the groove 35, the follower bearing 153can begin to move downward, and the upper edge 43′ of the cam groove 43in the conveyor sidewall 37 becomes an effective cam profile. Similarly,the upper edges 45′ of the grooves 45 become effective cam profilesdriving the follower bearing 157. As the actuator arm continues to movethe conveyor 27 toward the back of the tape drive, the cam profiles 43′,45′ drive the follower bearings 153, 157 attached to the cartridgeshuttle 49 downward. The path constraint groove 35 now limits themovement of the shuttle to a direct vertical drop, and the shuttlelowers the tape cartridge into its loaded position on top of the tapedrive motor. As the shuttle reaches the end of its linear travel, thecam profiles 43′, 45′ push the follower bearings 153, 157 to positionsessentially as shown in FIGS. 6-A and 6-B.

The three loading cam profiles formed by the grooves 43, 45 shown inFIGS. 6-A and 6-B lower the cartridge relatively evenly, to a positionof flat engagement of the drive gear within the cartridge to the drivegear on the motor. However, because of the different dimensions of thecam follower bearings 153, 157 and the attendant different contours ofthe back edges 43″, 45″ of the grooves, the cam action and attendantlift forces during unloading are different on each side of the cartridgeshuttle. Specifically, as the actuator arm 121 moves the conveyor 27back toward the front of the drive (right to left in FIGS. 6-A, 6-B),the trailing edges 45″ of the smaller grooves 45 in the left sidewall 41engage the smaller diameter follower bearings 157 first. As such, theleft wall of the conveyor 27 applies an upward force to the left side ofthe shuttle 49 before any upward force is applied to the right side ofthe shuttle. This produces a torque or twist on the cartridge 91, andthe plane of the plate is not lifted in parallel to the plane of themagnet, so as to help separate the plate in the cartridge drive gearfrom the magnet in the motor drive gear. As the conveyor motioncontinues, the trailing edge 43″ of the larger groove 43 in the rightsidewall 37 engages the larger diameter follower bearing 153 to lift theright side of the shuttle. Further movement of the conveyor lifts theshuttle and cartridge along the path defined by the path constraintgroove 35. Still further movement of the conveyor then moves the shuttleand cartridge laterally back toward the bezel opening as constrained bythe groove 35, to complete the unloading operation.

FIG. 7 shows the base 9 and the loader assembly 11 of the tape drive 1in an exploded view. This view also illustrates two aspects of theinvention incorporated into the base 9.

First, the base 9 includes two load balancing springs 161. These springsengage the bottom surface of the tape cartridge shuttle, when theshuttle and cartridge are lowered into the fully loaded position. Thelowering of the shuttle compresses the load balancing springs 161. Thecompressed springs apply an upward force to the shuttle. When theactuator begins to raise the shuttle, the spring forces assist inraising the shuttle and separating the plate in the cartridge drive gearfrom the magnet in the motor drive gear.

The springs 161 also create a force opposing lowering of the shuttle andcartridge into the final position. The cam profiles 43′, 45′ for loadinginclude small regions 165 (FIGS. 6-A, 6-B) to overcome this force.Specifically, each of these cam profiles includes a region 165 thatextends adjacent the bend. Each region 165 has a low pressure angle.These regions of the cam profiles apply forces to the cam followers toovercome the highest reaction from the springs 161 after the magneticattraction ends during lowering of the cartridge, e.g. after the metalplate engages the magnet. The camming by the regions 165 also overcomespressure forces of the cantilevered springs 79 to separate the bottomplate of the shuttle from the lower surface of the cartridge.

FIG. 7 also shows two features extending upward from the base 9.Preferably, these extruded features 163 are substantially conical, withnarrower ends upward. The features are located on the base to engage theholes 113 formed in the bottom of the cartridge 91 (FIG. 3-A).Registration of the conical features in the holes 113 serves toaccurately align the tape cartridge in its lowermost position.

It may be helpful to consider the sequence of operations involved inloading a tape cartridge 91 into the tape drive 1. Initially, a user oran automated mechanism inserts the tape cartridge through a bezelopening (not shown) into the tape drive 1. Specifically, the cartridge91 is inserted and pushed to the back of the cartridge shuttle 49. Theextruded features 59 in left sidewall 57 of shuttle 49 push thecartridge to the right side of the shuttle 49. As the cartridge 91 isforwarded into the shuttle 49, bent feature 73 extending inwards fromthe back of the right sidewall 53 engages the tape-protecting door andslides the door toward the rear of the cartridge. This opens the door,exposing a leader pin attached to the end of the recording tape, makingthe pin accessible to a grabbing feature in the load arm assembly.

As the cartridge is pushed into the shuttle 49 and approaches its properlocation, the flat springs 155 apply pressure and eventually the flatsprings 155 engage notches in the lower edges of the cartridge. Thefront of the cartridge 91 also engages the stops 61. The cantileveredsprings 79 apply downward pressure on the cartridge. The cartridge isnow in a stable position for transport. The insertion of the cartridgealso engages the cartridge-in sensor switch 69, which triggers theloader motor assembly 131.

The motor 133, gear reduction box, and gear train drive the worm gear135 to rotate about its horizontal axis, and the worm gear 135 engagesthe teeth of the gear 129 to rotate the actuator arm 121 clockwise aboutthe vertical pivot axis formed by the pin 127 and the opening 125 (seeFIG. 4-A). As the actuator arm 121 rotates, the front edge 141′ ofgroove 141 makes normal contact (90° pressure angle) with the followerbearing 33′ attached to the top of the cartridge conveyor 27 (FIG. 5-A).The rotational movement of the arm 121 therefore produces a linearmovement of the conveyor 27 back into the tape drive 1.

The linear motion of the conveyor 27 initially induces a linear motionof the tape cartridge shuttle assembly 47 along the path constraintgroove 35 in the frame housing 13. However, after the cam followerbearing 153 attached to the tape cartridge shuttle 49 reaches the end ofthe horizontal portion of the groove 35, the inclined cam profiles 43′,45′ formed in the side plates of the conveyor induce a downward verticalmovement of the tape cartridge shuttle assembly 47.

As the shuttle lowers the cartridge, the conical features 163 on thebase 9 (FIG. 7) engage the holes 113 in the bottom of the cartridge(FIG. 3-A), to accurately align the tape cartridge in its lowermostposition. Also, the ring-shaped magnet 107 of the motor drive gear 105exerts a magnetic attraction force on the metal plate 97 in the centraldrive gear 95 of the tape cartridge, to pull the teeth 99, 109 of thesetwo gears into a positive mesh. The cantilevered springs 79 also providedownward pressure to help position the cartridge in full engagement withthe motor and base, and those springs provide some vertical buffering ofthe cartridge in the fully engaged position with respect to thecartridge shuttle assembly 47.

The regions 165 of the cam profiles apply the final pressure on theshuttle to offset the upward forces created by the springs 161 and thecantilevered springs 79. The regions 165 apply sufficient force tocontinue movement of the shuttle 49, even after engagement of the gearsand after the cartridge comes to rest. This continued downward motion ofthe shuttle achieves a small separation (e.g. 0.3 mm) between the lowerplate 55 of the shuttle 49 and the bottom of the cartridge. The regions165 have a low pressure angle and may be slightly curved, to achieve ahigh force for a short throw or travel of the conveyor 27 relative tothe cam followers 153, 156 and the shuttle 49. The high force is neededto overcome the sum of the various spring forces.

After this lowering of the shuttle and the cartridge, the loader motorassembly 131 stops, and the movement of the actuator arm 121, theconveyor 27 5 and the shuttle assembly 47 stops. The tape cartridge isin the fully loaded position. The leader pin attached to the end of themagnetic tape within the cartridge is accessible through the open tapedoor. A grabbing feature of the load arm assembly (not shown) grabs theleader pin and draws the pin to the center of the take-up reel (also notshown). The data read/write process may now commence.

It also may be helpful to consider the sequence of operations involvedin unloading a tape cartridge from the tape drive 1. A control signalcauses the tape drive motor 101 to rewind the tape into the cartridge,and the leader pin is released from the take-up reel and the load armassembly. A control signal is then applied to the loader motor assembly131. This signal causes the motor 133, gear reduction box, and geartrain drive the worm gear 135 to rotate in the opposite direction aboutits horizontal axis.

The magnetic attraction between the metal plate 97 and the magnet 107creates a force opposing the initial lifting of the cartridge 91. Thisplaces a high torque requirement on the loader motor. The inventionprovides two different mechanisms to help offset this torquerequirement. First, the compression springs 161 produce a force tendingto separate the cartridge from the drive motor and thus to separate theplate 97 and the magnet 107 within the gears 99, 109. Second, theunloading cam profiles 43, 45 and the associated cam follower bearings153, 157 are designed to twist the cartridge somewhat during initiallifting, so that the two planes of the plate 97 and the magnet 107 arenot parallel, and thus are easier to separate.

Continuing with the discussion of the unloading operation, the worm gear135 engages the teeth of the gear 129 to now rotate the actuator arm 121counterclockwise about the vertical pivot axis formed by the pin 127 andthe opening 125 (FIG. 4-A). As the actuator arm 121 rotates, the backedge 141″ of groove 141 makes normal contact (90° pressure angle) withthe follower bearing 33′ attached to the top of the cartridge conveyor27 (FIG. 4-B). This rotational movement of the arm 121 thereforeproduces a linear movement of the conveyor 27 from the back of the tapedrive 1 toward the front of the drive.

The forward linear motion of the conveyor 27 causes the trailing edges45″ of the smaller grooves 45 in the left sidewall 41 to engage thesmaller diameter follower bearings 157 first (FIG. 6-A). This producesan upward force on the left side of the shuttle assembly 47 and the tapecartridge, causing a torque on the cartridge, to help separate the metalplate 97 in the cartridge drive gear 95 from the magnet 107 in the motordrive gear 105. To further assist in separation of the gears andovercoming the magnetic attraction, the two compression springs 161 onthe base 9 apply upward forces to the bottom of the shuttle 49. As thelinear movement of the conveyor 27 continues, the trailing edge 43″ ofthe larger groove 43 in the right sidewall 37 engages the largerdiameter follower bearing 153 to lift the right side of the shuttle 49(FIG. 6-B). Further movement of the conveyor 27 lifts the shuttle 49 andthe cartridge 91 along the path defined by the path constraint groove35. Still further movement of the conveyor then moves the shuttle andcartridge laterally back toward the bezel opening as constrained by thegroove 35. When the conveyor 27 and the shuttle assembly reach the endof their range of travel toward the front of the drive, the cam follower153 trips the home position switch 151, and operation of the motor 133stops. At this point, the motion of the actuator arm, the conveyor 27and the shuttle assembly 47 stop, and the cartridge is accessiblethrough the bezel opening so as to allow a user or a mechanism towithdraw the cartridge.

As shown by the drawings and the above discussion, the automatic tapecartridge loader mechanism of the present invention provides aneffective system for loading and unloading cartridges, while minimizingthe space occupied by the loader. The loader illustrated in the drawingsis only slightly larger than the tape cartridge itself. The inventivearrangement of load balancing springs assists in separating the gears,overcoming magnetic forces of engagement, and reducing torquerequirements during unloading. The springs, however, require minimalspace within the design envelopes of the drive and its loader mechanism.

The inventive tape loader also is quite durable and has a long servicelife. A loader mechanism in accord with the invention was designed for auseful life of at least 300,000 loading/unloading cycles. An actual testunit has completed over 1,500,000 cycles without jam or failure and hasexhibited virtually no component wear.

Those skilled in the art will recognize that the present inventionadmits of a number of modifications, within the spirit and scope of theinventive concepts. While the foregoing has described what areconsidered to be preferred embodiments of the invention it is understoodthat various modifications may be made therein and that the inventionmay be implemented in various forms and embodiments, and that it may beapplied in numerous applications, only some of which have been describedherein. It is intended by the following claims to claim all suchmodifications and variations which fall within the true scope of theinvention.

What is claimed is:
 1. An automatic tape cartridge loader, for loading atape cartridge into a tape drive for reading and writing of data on atape within the cartridge, the tape loader comprising: a shuttle forreceiving the tape cartridge; means for automatically moving the shuttleto and from a position within the loader in which a gear within the tapecartridge engages a gear coupled to a drive motor of the tape drive; abase; and a pair of compression springs mounted on the base forcompression between the shuttle and the base by movement of the shuttleto said position, for producing a force opposing movement of the shuttleto said position and assisting movement of the shuttle from saidposition in such manner as to assist in separating the gear within thetape cartridge from the gear coupled to the drive motor.
 2. A tapecartridge loader as in claim 1, wherein the means for automaticallymoving the shuttle comprises: a conveyor automatically actuated forlinear motion; at least one cam profile on the conveyor; and at leastone cam follower bearing attached to the shuttle engaging and followingthe at least one cam profile to automatically move the shuttle to saidposition within the loader in response to linear motion of the conveyor.3. A tape cartridge loader as in claim 2, wherein the cam profilecomprises a region having a low pressure angle for applying force to thecam follower bearing to overcome the force of the springs opposing themovement of the shuttle to said position.
 4. A tape cartridge loader asin claim 2, wherein: the conveyor comprises a first sidewall and asecond sidewall opposite the first sidewall; the at least one camprofile comprises a first cam profile formed in the first sidewall and asecond cam profile formed in the second sidewall; and the at least onecam follower bearing comprises a first bearing attached to one side ofthe shuttle and a second bearing attached to an opposing side of theshuttle, the first bearing engaging the first cam profile and the secondbearing engaging the second cam profile.
 5. A tape cartridge loader asin claim 4, wherein each of the first and second cam profiles comprisesa region having a low pressure angle for applying force to overcome theforce of the springs opposing the movement of the shuttle to saidposition.
 6. A tape cartridge loader as in claim 2, further comprisingautomatic actuator means, coupled to the conveyor, for automaticallyinducing back and forth linear motion of the conveyor.
 7. A tapecartridge loader, for automatically loading a tape cartridge into a tapedrive for reading and writing data on a tape within the cartridge, theloader comprising: a base; a frame housing secured to the base; aconveyor mounted for linear motion in a first direction within the framehousing during loading of the tape cartridge and for linear motion in asecond direction within the frame housing during unloading of the tapecartridge, an actuator system coupled to the conveyor, automaticallydriven for inducing linear motion of the conveyor in the first andsecond directions; a shuttle for receiving the tape cartridge; at leastone cam profile and at least one cam follower bearing, coupling theshuttle to the conveyor, for moving the shuttle to and from a positionwithin the loader in which a gear within the tape cartridge engages agear coupled to a drive motor of the tape drive in response to thelinear motions of the conveyor during loading and unloading of the tapecartridge, respectively; and at least one spring for producing a forceopposing movement of the shuttle to said position and assisting movementof the shuttle from said position in such manner as to assist inseparating the gear within the tape cartridge from the gear coupled tothe drive motor, wherein the at least one cam profile comprises: a firstinclined section having a high pressure angle for inducing a substantialportion of the motion of the at least one cam follower bearing and theshuttle toward said position; and a second section having a low pressureangle for inducing additional motion of the at least one cam followerbearing and the shuttle to reach said position and overcome the opposingforce produced by the at least one spring.
 8. A tape cartridge loader asin claim 7, wherein the second section induces motion of the shuttlepast said position, to produce a gap between a surface of the cartridgeand an adjacent surface of the shuttle.
 9. A tape cartridge loader as inclaim 8, wherein the shuttle comprises a plurality of cantileveredsprings for applying spring force toward the tape drive motor to thecartridge within the shuttle and for buffering the cartridge within theshuttle when the shuttle moves past said position.
 10. A tape cartridgeloader, for automatically loading a tape cartridge into a tape drive forreading and writing data on a tape within the cartridge, the loadercomprising: a base; a frame housing secured to the base; a conveyormounted for linear motion in a first direction within the frame housingduring loading of the tape cartridge and for linear motion in a seconddirection within the frame housing during unloading of the tapecartridge, an actuator system coupled to the conveyor, automaticallydriven for inducing linear motion of the conveyor in the first andsecond directions; a shuttle for receiving the tape cartridge; at leastone cam profile and at least one cam follower bearing, coupling theshuttle to the conveyor, for moving the shuttle to and from a positionwithin the loader in which a gear within the tape cartridge engages agear coupled to a drive motor of the tape drive in response to thelinear motions of the conveyor during loading and unloading of the tapecartridge, respectively; and at least one spring for producing a forceopposing movement of the shuttle to said position and assisting movementof the shuttle from said position in such manner as to assist inseparating the gear within the tape cartridge from the gear coupled tothe drive motor, wherein the at least one spring comprises a compressionspring attached to the base for compression by the shuttle as it movesto said position.
 11. A tape cartridge loader, for automatically loadinga tape cartridge into a tape drive for reading and writing data on atape within the cartridge, the loader comprising: a base; a framehousing secured to the base; a conveyor mounted for linear motion in afirst direction within the frame housing during loading of the tapecartridge and for linear motion in a second direction within the framehousing during unloading of the tape cartridge, an actuator systemcoupled to the conveyor, automatically driven for inducing linear motionof the conveyor in the first and second directions; a shuttle forreceiving the tape cartridge; at least one cam profile and at least onecam follower bearing, coupling the shuttle to the conveyor, for movingthe shuttle to and from a position within the loader in which a gearwithin the tape cartridge engages a gear coupled to a drive motor of thetape drive in response to the linear motions of the conveyor duringloading and unloading of the tape cartridge, respectively; and a pair ofsprings attached to the base for producing a force opposing movement ofthe shuttle to said position and assisting movement of the shuttle fromsaid position in such manner as to assist in separating the gear withinthe tape cartridge from the gear coupled to the drive motor.
 12. A tapecartridge loader, for loading a tape cartridge into a tape drive forreading and writing data on a tape within the cartridge, the tape loadercomprising: a conveyor mounted for linear motion, the conveyor havingopposing first and second sidewalls, a first cam profile in the firstsidewall, and a second cam profile in the second sidewall; a shuttle forreceiving the tape cartridge; a first cam follower bearing attached to afirst side of the shuttle in cam engagement with the first cam profile;a second cam follower bearing attached to a second side of the shuttleopposite to the first side of the shuttle, the second cam followerbearing being in engagement with the second cam profile, wherein: thesecond cam follower bearing is larger than the first cam followerbearing, and the first and second cam profiles are contoured so thatinteraction of the first and second cam follower bearings respectivelywith the first and second cam profiles during unloading of the tapecartridge from the loader provides a difference between forces onopposing sides of the tape cartridge.
 13. A tape cartridge loader as inclaim 12, in combination with: a tape drive motor; a tape drive gearcoupled for rotation by the tape drive motor; and a magnet secured tothe tape drive gear for magnetically attracting a gear within the tapecartridge, wherein the different forces on opposing sides of the tapecartridge help to separate the gear within the tape cartridge from thetape drive gear during unloading of the tape cartridge.
 14. A tapecartridge loader as in claim 12, further comprising at least one springpositioned to apply a load balancing force to assist in initial movementof the shuttle during the unloading of the tape cartridge.
 15. A tapecartridge loader, for loading a tape cartridge into a tape drive forreading and writing data on a tape within the cartridge, the tape loadercomprising: a conveyor mounted for linear motion, the conveyor havingopposing first and second sidewalls, a first cam profile in the firstsidewall, and a second cam profile in the second sidewall; a shuttle forreceiving the tape cartridge; a first cam follower bearing attached to afirst side of the shuttle in cam engagement with the first cam profile;a second cam follower bearing attached to a second side of the shuttleopposite to the first side of the shuttle, the second cam followerbearing being in engagement with the second cam profile, wherein: thesecond cam follower bearing is larger than the first cam followerbearing, the first and second cam profiles are contoured so thatinteraction of the first and second cam follower bearings respectivelywith the first and second cam profiles during unloading of the tapecartridge from the loader provides different forces on opposing sides ofthe tape cartridge, and the first and second cam profiles are contouredsuch that motion of the conveyor during unloading causes the first camprofile to apply force through the first cam follower bearing to theshuttle prior to the second cam profile applying force through thesecond cam follower bearing to the shuttle.
 16. A tape cartridge loaderas in claim 15, wherein the cam profiles are inclined relative to thelinear motion of the conveyor.
 17. A tape cartridge loader as in claim15, further comprising: a third cam profile formed in the first sidewallof the conveyor; and a third cam follower bearing attached to the firstside of the shuttle for interaction with the third cam profile.
 18. Atape cartridge loader as in claim 17, wherein the third cam followerbearing is substantially similar in size to the first cam followerbearing, and the third cam profile is similar in contour to the firstcam profile.
 19. A tape cartridge loader as in claim 15, furthercomprising a frame housing, wherein the conveyor is mounted for linearmotion within the frame housing.
 20. A tape cartridge loader as in claim19, further comprising: an actuator coupled to the frame housing forinducing the linear motion of the conveyor; and a motor coupled to theactuator for driving the actuator in response to a drive signal.
 21. Atape cartridge loader, for loading a tape cartridge into a tape drivefor reading and writing data on a tape within the cartridge, the tapeloader comprising: a frame housing; a conveyor mounted for linear motionwithin the frame housing, the conveyor having opposing first and secondsidewalls, a first cam profile in the first sidewall, and a second camprofile in the second sidewall; a shuttle for receiving the tapecartridge; a first cam follower bearing attached to a first side of theshuttle in cam engagement with the first cam profile; a second camfollower bearing attached to a second side of the shuttle opposite tothe first side of the shuttle, the second cam follower bearing being inengagement with the second cam profile, wherein: the second cam followerbearing is larger than the first cam follower bearing, the first andsecond cam profiles are contoured so that interaction of the first andsecond cam follower bearings respectively with the first and second camprofiles during unloading of the tape cartridge from the loader providesdifferent forces on opposing sides of the tape cartridge, the framehousing comprises a path constraint groove comprising a first sectionparallel to the linear motion of the conveyor and a second sectionperpendicular to the first section; and one of the cam follower bearingsalso interacts with the path constraint groove to limit motion of theshuttle to a path defined by the path constraint groove.
 22. A tapecartridge loader as in claim 21, wherein the one cam follower bearingcomprises the second cam follower bearing.
 23. A tape drive for a datatape cartridge comprising: a tape drive motor; a tape drive gear coupledfor rotation by the tape drive motor; a magnet secured to the tape drivegear for magnetically attracting a gear within the tape cartridge; andan automatic loader for loading the tape cartridge such that the tapedrive gear engages the gear within the tape cartridge and for unloadingthe tape cartridge from engagement and from the tape drive, theautomatic loader comprising: (a) a frame housing; (b) a conveyor mountedfor linear motion in a first direction within the frame housing duringloading of the tape cartridge and for linear motion in a seconddirection within the frame housing during unloading of the tapecartridge, the conveyor having first and second sidewalls, a firstgroove formed in the first sidewall, and a second groove formed in thesecond sidewall, each of the first and second grooves having a camprofile for loading and a cam profile for unloading; (c) an actuatorcoupled to the conveyor, automatically driven for inducing linear motionof the conveyor in the first and second directions; (d) a shuttle forreceiving the tape cartridge; (e) a first cam follower bearing, attachedto a first side of the shuttle, for cam engagement with the cam profilesof the first groove; and (f) a second cam follower bearing, attached toa second side of the shuttle opposite to the first side of the shuttle,for engagement with the cam profiles of the second groove, the secondcam follower bearing being larger than the first cam follower bearing,wherein: the loading cam profiles of the first and second grooves arecontoured so that interaction with the first and second cam followerbearings respectively during tape cartridge loading induces a motion ofthe shuttle for retracting the tape cartridge into the frame housing andinto engagement of the gear within the tape cartridge with the tapedrive gear, and the unloading cam profiles of the first and secondgrooves are contoured so that interaction with the first and second camfollower bearings respectively during unloading of the tape cartridgefrom the loader provides different forces on opposing sides of the tapecartridge, to assist in overcoming attraction and engagement by themagnet and in separation of the gear within the tape cartridge fromengagement with the tape drive gear.
 24. A tape drive as in claim 23,wherein: the frame housing comprises a path constraint groove comprisinga first section parallel to the linear motion of the conveyor and asecond section perpendicular to the first section; and one of the camfollower bearings also interacts with the path constraint groove tolimit motion of the shuttle to a path defined by the path constraintgroove.
 25. A tape drive as in claim 24, wherein the one cam followerbearing is the second cam follower bearing.
 26. A tape drive as in claim23, wherein the actuator comprises: an arm rotatably coupled to theframe housing and coupled to the conveyor; and a motor for selectivelyrotating the arm in opposite directions during loading and unloadingoperations.
 27. A tape drive as in claim 23, wherein: the first sidewallhas a third groove, edges of which provide a cam profile for loading anda cam profile for unloading; and the loader further comprises a thirdcam follower bearing attached to the first side of the shuttle forinteraction with the cam profiles of the third groove.
 28. A tape driveas in claim 27, wherein the third cam follower bearing is substantiallysimilar in size to the first cam follower bearing, and contours of thecam profiles of the third groove are substantially similar to contoursof the cam profiles of the first groove.
 29. A tape drive as in claim23, wherein the shuttle comprises a plurality of cantilevered springsfor applying spring force toward the tape drive motor to a cartridgewithin the shuttle.
 30. A tape drive as in claim 29, wherein the shuttlefurther comprises at least one spring for engaging a registration notchin the tape cartridge when the tape cartridge is fully inserted into theshuttle.
 31. A tape drive as in claim 29, wherein the shuttle furthercomprises at least one extruded feature for justifying the tapecartridge toward one side of the shuttle when the tape cartridge isinserted into the shuttle.
 32. A loader, for automatically loading atape cartridge into a tape drive for reading and writing data on a tapewithin the cartridge, the loader comprising: a cartridge shuttle forreceiving the tape cartridge and moving to and from a position in whichthe tape cartridge is loaded within the tape drive; and means forproducing a force to assist in separating the gear within the tapecartridge from the gear coupled to the drive motor.